In this project advanced engineering techniques, including applied mathematics, are applied to obtain quantitative as well as objective information on the structure of neuron networks in the nematode and in the visual systems of the vertebrate and invertebrate. Research is being conducted at both light and electronmicroscopic levels. In the former application, images of Golgi-silver impregnated or methylene-blue stained neurons are digitized and optically-sectioned either using a flying spot scanner or using a TV camera and stored on digital tapes. The images are filtered, edge-enhanced and combined to reproduce a 3-D stereopair of the reconstructed neurons. We plan to project the reconstructed images on the tangential or radial planes to abstract structural parameters which might underly the functional characteristics of a class of neurons. In the latter application, 3-D reconstruction of the plain or Golgi-electron microscopic preparations is achieved through an interactive device by which a human observer traces contour of a given neuron in serial sections. Images are stored and 3-D reconstructed in the computers.